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California’s Joshua Trees Are Under Threat

Climate change could decimate the iconic tree for future generations

These shaggy icons may be long gone by next century due to climate change. (Guillermo Torres (Flickr/Creative Commons))
smithsonian.com

You may not know the name Yucca brevifolia, but you likely know the plant species by sight. With prickly, bayonet-like leaves, the plant—otherwise known as the Joshua tree—is so famous it has its own national park. But the future may not be bright for these iconic plants. As Lauren Sommer reports for NPR, climate change could one day wipe out California’s Joshua trees for good.

Cameron Barrows, an ecologist at the University of California, Riverside, tells Sommer that he expects their habitat to shrink by as much as 90 percent by the end of the century. That’s consistent with numbers Barrow has been projecting since 2007, when he began the first year of a 20-year-long biological study at Joshua Tree National Park. In 2015, National Geographic’s Osha Gray Davidson reported that Barrows’ first year of surveying revealed very few trees in up to 30 percent of the plants’ normal range.

Nine years later, the fight to preserve Joshua trees continues. Though the trees usually live 150 years or more, the plants, which are a species of Yucca, which is a member of the Lily Family, can’t survive when there is no groundwater to draw on.

That’s a big problem in desert areas like Joshua Tree National Park, which straddles the Colorado Desert and the Mojave Desert. Scientists project that by 2050, the mean average temperature in the Mojave will rise four degrees Fahrenheit and that precipitation may drop by up to 2.6 percent per year.

Joshua trees are survivors—their extensive root systems and shaggy, spreading leaves mean they’re prepared to suck up any and all precipitation that comes their way. But the saplings are what worry conservationists. Since their root systems are much shallower, they are particularly vulnerable to hotter, more arid years.

So just how many baby Joshua trees are left? “The only way to know,” writes Barrows, “is to get outside and count plants.” Perhaps Barrows’ census—and human attempts to quell climate change—could one day save the surreal trees that make California’s desert so iconic.

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